Longitudinal associations between structural prefrontal cortex and nucleus accumbens development and daily identity formation processes across adolescence

Abstract

We tested whether adolescents with daily high identity uncertainty showed differential structural brain development across adolescence and young adulthood. Participants (N = 150, M_ageT1 15.92 years) were followed across three waves, covering 4 years. Self-reported daily educational identity and structural brain data of lateral prefrontal cortex (lPFC)/anterior cingulate cortex (ACC), medial PFC, and nucleus accumbens (NAcc) was collected across three waves. All hypotheses were pre-registered. Latent class growth analyses confirmed 2 identity subgroups: an identity synthesis class (characterized by strong commitments, and low uncertainty), and an identity moratorium class (high daily identity uncertainty). Latent growth curve models revealed, on average, delayed maturation of the lateral PFC/ACC and medial PFC and stable NAcc. Yet, adolescents in identity moratorium showed lower levels and less decline in NAcc gray matter volume. Lateral PFC/ACC and medial PFC trajectories did not differ between identity subgroups. Exploratory analyses revealed that adolescents with higher baseline levels and delayed maturation of lateral PFC/ACC and medial PFC gray matter volume, surface area, and cortical thickness reported higher baseline levels and stronger increases of in-depth exploration. These results provide insight into how individual differences in brain development relate to fluctuations in educational identity development across adolescence and young adulthood.

Keywords: Adolescent identity formation; Lateral PFC/ACC; Longitudinal; Medial PFC; Nucleus accumbens; Structural brain development.

Fig. 1

Regions of interest for the current study. Panel A) shows medial and lateral views of the lateral PFC/ACC (in green), which consisted of the combination of the rostral middle frontal gyrus, caudal middle frontal gyrus, caudal anterior cingulate gyrus, and superior frontal gyrus from the Desikan-Killiany-Tourville cortical parcellation atlas (Klein and Tourville, 2012) and the medial PFC (in blue), which was defined as Brodmann area 10 (mBA10) from Mills et al., 2014a,; https://figshare.com/articles/Social_Brain_Freesurfer_ROIs/726133). Panel B) displays the nucleus accumbens, which consisted of ‘Accumbens area’ from the FreeSurfer Aseg atlas (Fischl et al., 2002). For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.

Fig. 2

Final two class solution of the latent class growth curve analysis (LCGA) showing the estimated trajectories fo commitment level, commitment fluctuations, and reconsideration. For reasons of clarity we visualized the estimated trajectories for all three variables and not the raw individual level trajectories. Average age for each wave is presented on the x-axis.

Fig. 3

Observed individual trajectories for each region of interest. PFC = prefrontal cortex; ACC = anterior cingulate cortex; NAcc = nucleus accumbens.